Download Indications for Cardiac Catheterization in the Diagnosis and

Indications for Cardiac Catheterization in the
Diagnosis and Management of Coronary
Artery Disease
GEORGE W VETROVEC, M.D.
Assistant Professor of Medicine and Cardiology, and Director, Cardiac Catheterization Laboratory,
Medical College of Virginia, Richmond, Virginia
In 1979 coronary ang iography remains
the standard test for diagnosing the presence
and extent of coronary artery disease. Noninvasive studies such as exercise testing are
only relative predictors of coronary anatomy.
Therefore, to define spec ifical ly whether or not
coronary disease ex ists in a given patient and, if
present , to delineate its location, severity and
the potential for bypass surgery , a coronary
angiog ram is th e test to obtain . Th e purpose of
this paper is to discuss indicati ons for coronary
ang iography in the management of patients
with established or suspected coronary disease.
Figure 1 shows a schematic representation of the normal cardiac blood supply The left
and right coronaries exit directly from the aorta,
and the left main coronary divides into two major branches , the left anterior descending and
the circumflex vessels. It is important to note the
extensive blood supply to the heart-mainly the
left ventricle-through the left main coronary
and its branches. Therefore , the left main coronary is frequently considered in a special class
wh en discussing coronary artery disease. Other
important vessels include th e left anterior descend ing, the circumflex and the right coronary
arteries . The term "s ingle- ", "do uble- ," or
''tripl e-vessel disease '' refers to the number of
th ese three important vessels involved with significant disease. Obstructive lesions of the coroCorrespondence and reprint req uests to Dr. George
W Vetrovec, Box 36, Medical College of Virginia, Richmond, VA 23298 .
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15(1)16-2 1, 1979
naries represent the bui ld-up of atherosc lerotic
material which decreases the vessel lumen and
thereby decreases blood flow through the vessel. During coronary ang iography, rad iopaque
dye is inJected selectively into each coronary artery to all ow visualization of each vessel and its
majo r branches.
Figure 2 illustrates a sing le-frame cine
from such a procedure; the sign ificant atherosclerotic lesion is clearly demarcated. Therefore , using this techn ique, the extent and location of coronary artery lesions can be
specifica ll y identified.
Table 1 lists seven indications for coronary ang iography. Consid erab le controversy
continues to exist about the overall benefits of
coronary bypass surgery and therefore it is extremely difficult to be unequivocal in li sting
one's indi cations for coronary ang iography.
However, the general gu idelines given here are
thought to be the most reasonable , although
clini cal circumstances must be carefu ll y analyzed for each patient prior to proceeding to
coronary ang iography.
Symptomatic Indications
The first and probably most frequent indication for coronary angiography is failure of a
patient to respond to reasonable medical management; the term " reasonable medical management'' is used because of the wide response of patients to medical treatment . Some
patients ' response is less than ideal because of
poor drug comp li ance while others have intoler-
able side effects to the medications such as severe protracted headaches associated with nitrate administration, or significant fatigue or bad
dreams associated with propranolol. In addition,
a prior history of asthma or congestive heart failure is a contraindication for the use of propranolol. Finally , despite adequate medical
management, some patients remain incapacitated because of their chest pain In any situation in which a patient fails to get adequate
symptomatic benefit from medical treatment
and /or has significant side effects associated
with the treatment , coronary angiography
should be considered to determine if he or she
is a candidate for coronary bypass surgery
Clearly 80% to 90% of patients have a significant reduction in symptoms and medication requirements following coronary bypass surgery
and many of them remain symptom-free. 1 In a
study of 1 00 patients randomly assigned to
medical or surgical trea tment , Mathur and
Guinn 2 documented significantly improved
treadmill performance for post-bypass surgery
patients when compared with their medically
treated counterparts. Furthermore, subsequent
to treadmill testing , 70% of the surgical patients
had no angina while only 20% of the medical
Fig 2-Left main coron ary obstruction. The left corona ry
system seen in a lateral projection is fi lled with contrast medium during a contrast injection Note critica l left main artery
stenosis ( arro';l,j
group were angina-free Th ese data emphasize
th e symptomat ic benefits of coron ary bypass
surgery
In addition to symptomati c benefits of coronary bypass su rg ery , certai n subg roups of pati ents have improved longevity following this
procedure. Ongoing stud ies will con tinu e to better delineate th ese subgroups, but at present
those pati en ts with left main coronary artery disease appear to show improved function and
prognosis as a resuIt of the bypass operation.
Thi s fact is well illu strated by a three-year followup of the subgroup of patients with significant
left main artery di sease from the VA Cooperati ve Study 3 In thi s stud y, 1 2 (29%) of 41 med ically treated patients died in th e three-year follow-up compared to on ly 3 (7%) of 42 patients
in the surgica lly treated group; the differen ce
was significant (p ~ 0 .01 ). In addition , the ben-
1.
Fig 1-Schematic coronary ana tomy Th e right and left coronary arteries ari se from the aorta. Th e short main left (LC)
artery bifurcates in to two large branches, th e left an terior
descending (LAD) artery and the circumflex (CX) artery supplying most of the anteri or and lateral myocardial surface.
Th e ri ght coronary (RC) artery supplies th e in ferior myocardium through th e posterior descending (PD) artery .
2.
3.
4.
5.
6.
7.
TABLE
Indications for Coronary Angiography
Ang ina inadeq uately responsive to reasonable medica l
management
Un stabl e ang ina
Atypica l angina
"H igh-Risk " coronary patients
Undiagnosed chest pa in
Heart fai lure post-myocardial infarction
Recurrent ang ina post-coronary bypass surgery
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efit appeared to be greatest in those patients
with associated right coronary disease.
Therefore, patients who do not respond
well to reasonable medical treatment, and who
are surgical candidates have an excellent prospect for improved functional status following bypass surgery. Furthermore, patients with left
main vessel disease and perhaps yet-to-beproven other subgroups have improved longevity following the bypass operation.
Unstable Angina Pectoris
A second major consideration for coronary angiography is patients who have unstable
or rapidly worsening angina pectoris; in certain
instances, these patients may even be classified
as having pre-infaction angina . Most cardiologists feel that such patients should be stabilized
first, if possible, with vigorous medical treatment. This philosophy is supported by studies
suggesting that the risk of emergency coronary
angiography and bypass surgery to patients
with unstable angina is equal to the risk of initial
medical management as far as morbidity and
mortality are concerned4; however, patients
who do not respond to medical treatment are
candidates for angiography and coronary bypass surgery to relieve their persistent symptoms. For those patients who do respond to
medical treatment the question then arises as to
whether they should be catheterized and, if so,
when. Generally, it seems prudent to consider
angiography for young , active patients with unstable angina even though they respond to
medical treatment, as a review of the angiographic and historical data will show.
Coronary angiography on large groups of
patients who have had recent unstable angina
have shown a 1 0% to 1 5% incidence of left
main coronary disease. 4 5 This finding is important because these patients have improved survival following bypass surgery . In addition, from
5% to 20% of patients may show normal coronary angiograms; variability of this number relates to the criteria used in any given study for
the diagnosis of unstable angina. When accompanying electrocardiographic changes are required for the diagnosis of unstable angina, the
incidence of normal coronaries associated with
this chest pain syndrome is reduced . However,
identifying normal coronaries is important as
many patients are then found to have a noncardiac cause for their chest pain. Rarely, indi-
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CARDIAC CATHETERIZATI ON
viduals may have angina with normal coronaries, but generally these patients do well , with
infrequent symptoms and a much lower risk of
myocardial infarction than those patients with
obstructive coronary disease. Therefore, the diagnosis of normal coronaries allows one to be
much more positive in reassuring the patient
about long-term survival. In addition to these
subgroups, a majority of the remaining patients
with unstable angina have significant three-vessel disease, a group that many feel may benefit
from bypass surgery in terms of symptoms and
prognosis .
One third or more of non-surgical patients
who have unstable angina will have a subsequent unstable period within six months despite medical treatment. 5 Excluding left main
vessel disease , in randomized studies comparing medical versus surgical treatment for unstable angina, there was no significant difference in morbidity (subsequent myocardial
infarctions) and mortality when the two groups
were compared after four months or after 1 %
years.6 However, these studies emphasize the
improved functional performance seen in those
patients who undergo surgery. Considering the
higher incidence of left main vessel disease, the
moderately frequent occurrence of normal coronaries and the significant subsequent disability
of medically treated patients, coronary angiography is warranted in active individuals with unstable angina to better define the programs and
appropriate treatment plan.
Atypical Angina Pectoris
A third consideration for coronary angiography is in those patients who demonstrate
atypical or Prinzmetal type angina pectoris. This
syndrome is charactreized by chest pain at rest
with associated significant ST-segment elevations which are transient in nature. These patients are often subject to significant rhythm disturbances and / or conduction abnormalities
with the chest pain episodes. 7 Anatomically, patients with atypical angina may have either highgrade fixed obstructive lesions or normal coronaries with intermittent vessel spasm producing
the symptoms . These patients are frequently
difficult to manage medically, thus the distinction between significant obstructive disease
and spasm is important from the standpoint of
therapeutic options, as patients with significant
obstructive disease generally benefit from by-
pass surgery whereas patients with spasm do
not .
High-Risk Patients
Symptoms of angina do not correlate well
with the extent of disease. Ideally , one would
like to have a simple noninvasive test that would
identify those patients who have significant left
main vessel disease which derives so much
prognositc benefit from bypass surgery, but no
such test is available. However, certain exercise
test responses are considered suggestive of severe coronary artery disease which frequently
includes left main vessel disease. Table 2 lists
those high-risk abnormalities. Included in this
group 8 are patients who develop marked (2 mm
or greater) ST-segment depression with exercise testing , particularly at low levels of exercise
performance. In addition , the development of
ST-segment elevation on treadmill testing in an
area of the electrocardiogram not showing a
prior myocardial infarction is a significant predictor of severe proximal coronary disease if not
of left main vessel disease.9 Finally , patients
who develop hypotension at nonmaximal exercise performance are again likely to have significant disease . 10 Such hypotension suggests severe myocardial ischemia consistent with
marked proximal coronary artery disease . In
these high-risk patients coronary angiography is
important to delineate this anatomic abnormality.
Other high-risk patients include those who
have a history of prior myocardial infarction and
significant symptomatology and / or poor exercise test responses , particularly if they are in the
high-risk category listed above. Furthermore ,
subendocardial myocardial infarctions may represent another significant risk group . Fifty consecutive patients with a recent condition of this
type at the Mayo Clinic 11 showed a high frequency of symptomatic disability in a short-term
ten-month follow-up. Fifteen patients (30%) had
significant stable angina pectoris and nearly
half , 23 (46%) of 50 , developed unstable angina
over the short time of the study ; only 1 2 (24%)
of the 50 remained angina-free. Considering
the frequency of significantly limiting symptomatology in this study, early angiography in patients with a recent subendocardial myocardial
infarction seems warranted to identify those patients who are candidates for bypass surgery,
particularly in physically active individuals.
TABLE 2
Exercise Test Predictors of Potentially Severe
Coronary Disease
1 . Marked ST-seg ment depression
2. ST-seg ment eleva ti on in an area of non infarcti on of
th e ECG
3. Hypotension at nonmax ima l performa nce
Chest Pain Diagnosis
To this point , the discussion has centered
on the diagnosis of the extent of coronary disease. Another consideration for coronary angiography is specifically to exclude the existence
of coronary disease. Not every patient with
vague, intermittent or poorly defined chest discomfort is a candidate for a coronary angiogram ; however, there are those in whom noninvasive studies , including exercise testing and
perhaps thallium imaging , fail to demonstrate
clearly whether or not coronary artery disease
exists. Most of these patients have symptom
complexes with components that are both typical and atypical of angina . In addition , the concern about the possibility of co ronary disease
may be limiting these patients' lifestyles. In such
instances , coronary angiography is warranted
to provide a definitive diagnosis.
Congestive Heart Failure
Congestive heart failure after a myocardial
infarction can be a difficult management prob~
lem , particularly if it does not respond to routine
medical treatment for heart failure . Left heart
failure may be manifested either as a congested
state with recurrent pulmonary edema and
shortness of breath or as a low-output state in
which the patient's major complaints relate to
low forward cardiac output , that is , fatigue ,
weakness and exercise intolerance without
chest pain . Clinical findings frequently include
either a mitral regurgitation murmur, ventricular
gallop rhythms and / or a contour on apex palpation , suggesting a left ventricular aneurysm .
Anatomically , one wishes to know whether or
not there is a localized aneurysm or significant
mitral regurgitation . Cardiac catheterization of
patients who fail to respond to routine treatment
will delineate the severity and location of left
ventricular wall motion abnormalities as well as
whether or not there is significant valvular insufficiency. In addition , coronary angiograms
identify obstructive vessels which may exist in
the areas of remaining functional myocardium.
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CARDIA C CATHETERI ZATION /
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Patients with severe diffuse non-localized left
ventricular dysfunction are generally not candidates for bypass surgery , because in such instances the operative risk is increased and
there is no benefit in terms of reducing heart
failure. However, if a localized, correctable mechanical problem exists such as a left ventricular aneurysm or significant mitral regurgitation,
the condition of these patients may be significantly improved by surgical correction of the
appropriate defect with or without additional bypass surgery as dictated by the coronary anatomy.
Recurrent Angina Pectoris Post-Bypass
Surgery
Finally , those patients who have previously undergone bypass surgery and who developed recurrent angina pectoris may need angiography; as the frequency of bypass surgery
increases, so will the numbers of such patients.
Two factors determine the need for repeat coronary post-bypass angiography. First , if the recurrent angina occurs within one to two months
following bypass surgery , it is likely that one or
more vein bypass grafts have occluded. 12 In this
event the preoperative angiograms should be
reviewed and the anatomy discussed with the
surgeon. If the distal vessels suggest poor distal
runoff either angiographically and / or at the time
of surgery and the post-bypass flows were poor,
it is unlikely that reoperation will carry any better
chance of maintaining a patent graft, and consideration of repeat catheterization should be
postponed unless medical treatment fails to be
effective. Conversely , if flows were good at the
time of surgery and the distal runoff appeared
adequate, graft failure might be caused by a
technical problem resulting from surgery Reoperation could conceivably benefit such a patient , thus a repeat angiogram is warranted ;
however, early recurrent angina is most often
seen in patients with severe distal disease.
A further consideration for angiography is
the patient who has experienced marked symptomatic improvement for a long time following
the bypass operation. When recurrent angina
occurs in such a patient , the anatomic problem
is generally not in the graft but represents progression of the disease in the native circulation,
either distal to the graft insertion or in other nongraftable vessels . Depending on the symptomatology and the state of the other vessels at the
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CARDIAC CATHETERIZATION
time of surgery , it is reasonable to consider a repeat study in these patients, looking for other
potentially graftable vessels.
The foregoing discussion should provide a
reasonable approach to the utilization of cardiac
catheterization and coronary angiographic techniques in the diagnosis and management of patients with coronary artery disease. Combining
the functional performance information derived
from noninvasive tests with the anatomic abnormalities demonstrated with coronary ang iography provides the most thorough evaluation of
patients with coronary disease. The information
derived from coronary angiography is frequently
important in the prognostic and therapeutic decisions regarding patients with coronary disease.
Figures 1 and 2 are reproduced with permission from
B Soto, RO Russell , RE Moraski Radiographic A na tom y of
the Coronary Arteries: An Atlas. Mount Kisco (New York),
Futura Publishing Company , Inc , 1976.
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and 48 (Suppl Ill) 111141 - 14 5, 1973
3. TAKARO T , HULTGREN HN, LIPTON MJ, ET AL: The VA cooperative randomized study of surgery for coronary arterial occlusive disease. II . Subgroup wit h significa nt
left main lesions. Circ ula tion 54 (Suppl Ill) Ill : 1 0 7 - 117,
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SELDEN R, NEILL WA , RITZMANN LW, ET AL: Medical versus surgical therapy for ac ute coronary insufficiency. N
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1978 .
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